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<h2 align="center" style="text-align:center">Layout Guide</h2>
<h3><a name="native">Native Sizes (Window and Client)</a></h3>
<p>Because of the dynamic nature of the abstract layout IUP elements have implicit many types of size. But the native 
  elements have only two types of size: <b>Window</b> and <b>Client</b>. The <b>Window</b> size reflects the bounding 
  rectangle of the element. The <b>Client</b> size reflects the inner size of the window that excludes the decorations 
  and margins. For many elements these two sizes are equal, but for many containers they are quite different. See some 
  examples below.</p>
<div align="center">
  <center>
  <table border="0" cellpadding="0" cellspacing="1" width="100%">
    <tr>
      <td width="33%" class="style2">
      <p align="center">
      <img border="0" src="images/nativesize1.gif" width="297" height="199"></td>
      <td width="33%" class="style2">
      <p align="center">
      <img border="0" src="images/nativesize2.gif" width="210" height="146"></td>
      <td width="34%" class="style2">
      <p align="center">
      <img border="0" src="images/nativesize3.gif" width="268" height="204"></td>
    </tr>
  </table>
  </center></div>
<p>The IUP sizes (<strong>User</strong>, <strong>Natural</strong> and <strong>
Current</strong>) described below are all related to the <strong>Window</strong> 
size. </p>
<p>The native <b>Client</b> size is used only internally to reposition the elements in the abstract layout, but it is 
  available using the CLIENTSIZE attribute.</p>
<h3><a name="iup">IUP Sizes</a></h3>
<h4>Natural Size</h4>
<p>IUP does not require that the application specifies the size of any element. The sizes are automatically calculated 
  so the contents of each element is fully displayed. This size is called <b>Natural</b> size. The 
<b>Natural</b> size 
  is calculated just before the element is mapped to the native system and every 
time <strong>IupMap</strong> is called, even if the element is already mapped.</p>
<p>The <b>Natural</b> size of a container is the size that allows all the elements inside the 
container to be fully 
  displayed.
<span class="style1">Important</span>: even if the element is invisible its size 
will be included in the size of its containers, except when FLOATING=Yes.</p>
<p>So consider the following code and its result. Each button size is large enough to display their respective text. 
  If the dialog size is increased or reduced by the size handlers in the dialog borders the buttons do not move or 
  change their sizes.</p>
<p>But notice that some controls do not have contents that can provide a <strong>
Natural</strong> size. In this case they usually have SIZE or RASTERSIZE 
pre-set.</p>
<p>To obtain the last computed <strong>Natural</strong> size of the control in pixels, use the read-only 
attribute <strong>NATURALSIZE</strong>.</p>
  <table border="0" cellpadding="0" cellspacing="6" width="50%" id="AutoNumber2">
    <tr>
      <td width="50%" class="style2">
      <pre>dlg = iup.dialog
{
  iup.vbox
  {
    iup.button{title=&quot;Button Very Long Text&quot;},
    iup.button{title=&quot;short&quot;},
    iup.button{title=&quot;Mid Button&quot;}
  }
  ;title=&quot;IupDialog&quot;, font=&quot;Helvetica, Bold 14&quot; 
}
dlg:show()</pre>
      </td>
      <td width="50%" class="style2">
      <img border="0" src="images/naturalsize.gif" width="251" height="179"></td>
    </tr>
  </table>
<h4>Current Size and User Size (SIZE or RASTERSIZE)</h4>
<p>When the application defines the <a href="attrib/iup_size.html">SIZE</a> or 
<a href="attrib/iup_rastersize.html">RASTERSIZE</a> attributes, it changes 
the <b>User</b> size in IUP. The initial 
internal value is &quot;0x0&quot;. When set to NULL the <b>User</b> size is 
internally  set to &quot;0x0&quot;.</p>
<p>By default the layout computation uses the <strong>Natural</strong> size of 
the elements to compose the layout of the dialog, but if the <strong>User</strong> 
size is defined then it is used <span class="style1">instead</span> of the <strong>Natural</strong> size, 
except for containers (not including the dialog) where the <strong>User</strong> 
size will be used only if <span class="style1">bigger</span> than the <strong>Natural</strong> size. For the 
dialog, when the <strong>User</strong> size is not defined, the <strong>Natural</strong> 
size is used only if <span class="style1">bigger</span> than the <strong>Current</strong> size, so in this 
case the dialog will automatically increase its size to fit all its contents, 
but if the <strong>Natural</strong> size is smaller then the dialog size will 
remains the same, i.e. the dialog will not automatically shrink its size.</p>
<p>The returned value for SIZE or RASTERSIZE is the <b>Current</b> size in IUP. 
It returns the native 
<b>Window</b> size of the element after the element is mapped to the native system. Before mapping, the returned value is the
<b>User</b> size defined by SIZE or RASTERSIZE 
  attributes if any, otherwise they are NULL.</p>
<p>Defining the SIZE attribute of the buttons in the example we can make all have the same size. (In the following 
  example the dialog size was changed after it was displayed on screen)</p>
<table border="0" cellpadding="0" cellspacing="6" width="50%" id="AutoNumber2">
	<tr>
		<td width="50%" class="style2">
		<pre>dlg = iup.dialog
{
  iup.vbox
  {
    iup.button{title=&quot;Button Very Long Text&quot;, <b>size=&quot;50x&quot;</b>},
    iup.button{title=&quot;short&quot;, <b>size=&quot;50x&quot;</b>},
    iup.button{title=&quot;Mid Button&quot;, <b>size=&quot;50x&quot;</b>}
  }
  ;title=&quot;IupDialog&quot;, font=&quot;Helvetica, Bold 14&quot; 
}
dlg:show()</pre>
		</td>
		<td width="50%" class="style2">
		<img border="0" src="images/usersize.gif" width="279" height="214"></td>
	</tr>
</table>
<p>So when EXPAND=NO (see below) for elements that are not containers if&nbsp; 
<b>User</b> size is defined then the <b>Natural</b> size is ignored.</p>
<p>If you want to adjust sizes in the dialog do it after the layout size and 
positioning are done, i.e. after the dialog is mapped or after <b>IupRefresh</b> is 
called.</p>
<h4>EXPAND</h4>
<p>Another way to increase the size of elements is to use the EXPAND attribute. When there is room in the container to 
  expand an element, the container layout will expand the elements that have the EXPAND attribute set to YES, HORIZONTAL 
  or VERTICAL accordingly, even if they have the <b>User</b> size defined.</p>
<p>The default is EXPAND=NO, but for containers is EXPAND=YES.</p>
<p>Using EXPAND in the example, we obtain the following result:</p>
<table border="0" cellpadding="0" cellspacing="6" width="50%" id="AutoNumber2">
	<tr>
		<td width="50%" class="style2">
		<pre>dlg = iup.dialog
{
  iup.vbox
  {
    iup.button{title=&quot;Button Very Long Text&quot;},
    iup.button{title=&quot;short&quot;, <b>expand=&quot;HORIZONTAL&quot;</b>},
    iup.button{title=&quot;Mid Button&quot;, <b>expand=&quot;HORIZONTAL&quot;</b>}
  }
  ;title=&quot;IupDialog&quot;, font=&quot;Helvetica, Bold 14&quot; 
}
dlg:show()</pre>
		</td>
		<td width="50%" class="style2">
		<img border="0" src="images/expand.gif" width="251" height="179"></td>
	</tr>
</table>

<p>So for elements that are NOT containers, when EXPAND is enabled the <b>
Natural</b> size and the <b>User</b> size are ignored.</p>
<p>For containers the default behavior is to always expand or if expand is 
disabled they are limited to the <b>Natural</b> size. As a consequence (if the
<b>User</b> size is not defined in all the elements) the dialog contents can 
only expand and its minimum size is the <b>Natural</b> size, even if EXPAND is 
enabled for its elements. In fact the actual dialog size can be smaller, but its 
contents will stop to follow the resize and they will be clipped at right and 
bottom.</p>
<p align="center">
<img border="0" src="images/no_shrink.gif" width="153" height="189"></p>
<p>
If the expansion is in the same direction of the box, for instance 
expand=&quot;VERTICAL&quot; in the Vbox of the previous example, then the expandable 
elements will receive equal spaces to expand according to the remaining empty 
space in the box. This is why elements in diferent boxes does not align 
perfectly when EXPAND is set.</p>
<h4>SHRINK</h4>
<p>To reduce the size of the dialog and its containers to a size smaller than the
<b>Natural</b> size the SHRINK attribute of the dialog can be used. If set to 
YES all the containers of the dialog will be able to reduce its size. But be 
aware that elements may overlap and the layout result could be visually bad if 
the dialog size is smaller than its <strong>Natural</strong> size.</p>

<p>Notice that in the example the dialog inicial size will be 0x0 because it is 
not defined. The picture shown was captured after manually resizing the dialog. So when using 
SHRINK usually you will also need to set the dialog initial size.</p>

<table border="0" cellpadding="0" cellspacing="6" width="50%">
	<tr>
		<td width="50%" class="style2">
		<pre>dlg = iup.dialog
{
  iup.vbox
  {
    iup.button{title=&quot;Button Very Long Text&quot;},
    iup.button{title=&quot;short&quot;, expand=&quot;HORIZONTAL&quot;},
    iup.button{title=&quot;Mid Button&quot;, expand=&quot;HORIZONTAL&quot;}
  }
  ;title=&quot;IupDialog&quot;, <b>shrink=&quot;yes&quot;,</b> font=&quot;Helvetica, Bold 14&quot; 
}
dlg:show()</pre>
		</td>
		<td width="50%" class="style2">
		<img border="0" src="images/shrink.gif" width="153" height="189"></td>
	</tr>
</table>

<h3>Layout <a name="Hierarchy">Hierarchy</a></h3>
<p>The layout of the elements of a dialog in IUP has a natural hierarchy because of the way they are composed 
  together.  </p>
<p>To create a node simply call one of the pre-defined constructors like <b>
IupLabel</b>, <b>IupButton</b>, <b>IupCanvas</b>, and so on. To create a branch 
just call the constructors of containers like <b>IupDialog</b>, <b>IupFrame</b>,
<b>IupVBox</b>, and so on. Internally they all call
<a href="func/iupcreate.html">IupCreate</a> to create branches or nodes. To 
destroy a node or branch call <a href="func/iupdestroy.html">IupDestroy</a>.</p>
<p>Some of the constructors already append children to its branch, but you can 
add other children using <a href="func/iupappend.html">IupAppend</a> or
<a href="func/iupinsert.html">IupInsert</a>. To 
remove from the tree call <a href="func/iupdetach.html">IupDetach</a>.</p>
<p>For the element to be visible <a href="func/iupmap.html">IupMap</a> must be 
called so it can be associated with a native control. <b>IupShow</b>, <b>
IupShowXY</b> or <b>IupPopup</b> will automatically call <b>IupMap</b> before 
showing a dialog. To remove this association call <a href="func/iupumap.html">
IupUnmap</a>.</p>
<p>But there is a call order to be able to call theses functions that depends on 
the state of the element. As you can see from these functions there are 3 
states: <b>created</b>, <b>appended</b> and <b>mapped</b>. From <b>created</b> 
to <b>mapped</b> it is performed one step at a time. Even when the constructor 
receives the children as a parameter <b>IupAppend</b> is called internally. When 
you <b>detach</b> an element it will be automatically <b>unmapped</b> if 
necessary. When you <b>destroy</b> an element it will be automatically <b>
detached</b> if necessary. So explicity or implicity there will be a call to:</p>
<pre>IupCreate  -&gt; IupAppend -&gt; IupMap
IupDestroy &lt;- IupDetach &lt;- IupUnmap</pre>
<p>A more simple and fast way to move an element from one position in the 
hierarchy to another is using <a href="func/iupreparent.html">IupReparent</a>.</p>
<p>The dialog is the root of the hierarchy tree. To retrieve the dialog of any 
element you can simply call
  <a href="func/iupgetdialog.html">IupGetDialog</a>, but there are other ways to navigate in the hierarchy tree.</p>
<p>To get all the children of a container call <a href="func/iupgetchild.html">
IupGetChild</a> or 
<a href="func/iupgetnextchild.html">IupGetNextChild</a>. To get just the next control with the same parent use 
<a href="func/iupgetbrother.html">IupGetBrother</a>. To get the parent of a 
control call <a href="func/iupgetparent.html">IupGetParent</a>.</p>
<p>In Lua, if the element was created in Lua, you can access any child of the 
element using the notation &quot;elem[n][n]....&quot;, where n is the index of the child. 
For example:</p>
<pre>
dlg = iup.dialog
{
  iup.hbox
  {
    iup.button{title="Ok&quot;}, 
    iup.button{title="Cancel&quot;},
  }
}
cancel_button = dlg[1][2]
</pre>
<h3>Layout <a name="Display">Display</a></h3>
<p>The layout size and positioning is automatically updated by <b>IupMap</b>.
  <b>IupMap</b> also updates the dialog layout 
  even if it is already mapped, so using it or using <b>IupShow</b>, 
  <b>IupShowXY</b> or 
  <b>IupPopup</b> (they all call 
  <b>IupMap</b>) will also update the dialog layout. The layout size and 
positioning can be manually updated using 
  <a href="func/iuprefresh.html">IupRefresh</a>, even if the dialog is not 
mapped.</p>
<p>After changing containers attributes or element sizes that affect the layout the elements are NOT immediately repositioned. Call
  <b>IupRefresh</b> for an element inside the dialog to update the dialog layout. To force a redraw of an element 
without layout update call
<a href="func/iupupdate.html">IupUpdate</a>.</p>
<p>The Layout update is done in two phases. First the layout is computed, this 
can be done without the dialog being mapped. Second is the native elements 
update from the computed values.</p>
<p>The Layout computation is done in 3 steps: <strong>Natural</strong> size 
computation, update the <strong>Current</strong> size and update the position. </p>
<ul>
	<li>The <strong>Natural</strong> size computation is done from the inner elements up 
to the dialog (first for the children then the element). <strong>User</strong> 
	size (set by RASTERSIZE or SIZE) is used as the <strong>Natural</strong> 
	size if defined, if not usually the contents of the element are used to 
	calculate the <strong>Natural</strong> size.</li>
	<li>Then the <strong>Current</strong> size is computed starting at the dialog down to 
the inner elements on the layout hierarchy (first the element then the 
	children). Children <strong>Current</strong> size is computed according to 
	layout distribution and containers decoration. At the children if EXPAND is 
	set, then the size specified by the parent is used, else the natural size is 
	used. </li>
	<li>Finally the position is computed starting at the dialog down to the 
	inner elements on the layout hierarchy, after all sizes are computed.</li>
</ul>

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